1080

A nor’wester groans in the skeletal fingers of a devastated kamahi forest. It’s spring; these trees should be seizing the sun, turning it into exuberant explosions of flowers. But the canopy, that reticulated energy network of millions of leaves, is gone. Normally it would support a chiming carillon of tui, bellbirds and kaka singing for their lovers. But breeding burns a lot of fuel, and here, many birds won’t find enough sustenance to reach breeding condition—their metabolic switch won’t flip.

That’s because these kamahi trees are also the favoured fodder of another creature, the brushtail possum. Every night, millions of them devour an estimated 21,000 tonnes of New Zealand forest; the leaves, berries, fruit and flowers that would, in pre-pestilent times, have powered the procreation of our native wildlife.

Some birds, experienced breeders, may yet produce eggs and chicks, but it turns out that possums have a taste for those as well; surveillance cameras have caught them robbing nests. And if the possums don’t get them, there’s an excellent chance that rats or stoats or ferrets or weasels or cats or hedgehogs will.

Conservation in New Zealand is mostly about trying to protect native wildlife from the teeth and claws of this plague of our own making—a malignant invasion that has resulted in the extinction of more than 40 per cent of our bird species as well as three frogs, a bat, a freshwater fish, at least three lizards and an unknown number of insects.

Which is why, this spring day, you hear only an echo of the disappeared.

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Clyde Graf, a Hamilton hunter, has noticed it too, but he attributes much of this silence to a cluster of molecules—two carbon, two hydrogen, one fluorine, two oxygen and one sodium. Bind them and you have sodium monofluoroacetate, or 1080.

Clyde and his brother Steve grew up in the misty backblocks of the Urewera Ranges, in a tent with no floor. Their father fed them with what he could hunt—deer and pigs. The boys, in turn, became deer hunters. But, says Graf, 1080 “stuffed” the venison business, and the pair turned instead to making hunting and fishing videos.

Hunting interests and lifestyle environmentalists have linked arms to publicly oppose 1080, and to date, no research, government PR or consultation has assuaged their concerns.

In March, they released a DVD, Poisoning Paradise – Ecocide in New Zealand, an anti-1080 polemic which claims that the toxin kills native birds in vast numbers, poisons soils, persists in water and interferes with human hormones. According to Graf, Poisoning Paradise will shock viewers with “disturbing, shameful facts that will withstand scrutiny”.

In many ways, the Grafs’ DVD epitomises an enduring hostility towards 1080 by certain sectors of society. Our understanding of the poison has advanced considerably, the use of it has improved, and countless studies point to its obvious merit, as the salvation of much of our wildlife. Yet 1080 remains maligned, even loathed. Could it really be that bad?

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In fact, most of the claims made in Poisoning Paradise aren’t new. The poison has been used and studied in New Zealand since the 1950s. There are hundreds of peer-reviewed papers examining the behaviour, properties and persistence of 1080 and its toxicity in creatures from frogs to ferrets to farmhands. Many of these studies provide scientific evidence that contradict the claims made in the DVD and which continue to be perpetuated in the media and public opinion.

Take, for instance, the claim that 1080 contaminates our waterways. Between 1990 and 2008, Landcare Research tested 2098 water samples following 1080 operations. Only three per cent were found to contain traces of 1080 and, apart from one test suspected of contamination, the levels were around 0.2 parts per billion (ppb), well below the Ministry of Health drinking-water standard of 3.5 ppb. Similarly, tests on the toxin’s impact on freshwater invertebrates and fish found no measurable effect—even when exposed to 1080 baits at 10 times the normal density.

It is true that 1080 has killed native birds; smaller, lighter ones such as robins and tomtits are particularly susceptible. This lesson was learned in 1996 when poorly screened carrot baits killed hundreds of both species in the Pureora Forest Park in the central North Island. But DOC responded accordingly, introducing cereal baits, switching to much thinner sowing rates and using green dyes and masking agents in the bait to put the birds off eating it. All this significantly reduced bird deaths; no monitored tomtits died after a 1998 Pureora operation, and robin-nesting success subsequently jumped from 11 per cent to 72 per cent.

There has never been a documented case of human 1080 poisoning in New Zealand, but even the tightest safety procedures couldn’t prevent this collateral casualty.

DOC also conducted a study, between 1998 and 2002, tracking the fate of kereru and kaka through aerial 1080 carrot operations in Whirinaki Forest in the Bay of Plenty. Radio transmitters were
fitted to birds both inside and outside the drop zone and monitored for a fortnight after the operation. None of the 17 tagged kaka or 15 kereru died.

And in 2007, at the behest of DOC and the Animal Health Board—the two biggest users of 1080—the Environmental Risk Management Authority (ERMA) reassessed the poison. The hearings were vaunted as the ultimate scrutiny, the most complete evaluation of the state of our knowledge. ERMA staff reviewed reams of scientific literature before the panel heard 1400 submissions at public hearings around the country. In the end, it approved the continued use of 1080, conditional upon tighter controls and more research into alternatives.

Yet this has done nothing to appease opponents. Clyde Graf dismissed the review as “a sham; a total waste of time” and anti-1080 groups simply redoubled their efforts. That same year, pregnant women fled an aerial 1080 operation at Karamea on the West Coast on the advice of midwives, marking a new nadir in public perception. “Nobody can guarantee this substance does not cross the placental barrier,” Nelson District Health Board midwife Carol Craven told Danielle Yealands, an expectant mum. Paul Murray of KAKA 1080, a group sworn to banning the substance on the West Coast, justified the advice: “Sodium monofluoroacetate (1080) is a known endocrine disruptor and…developing fetuses are thought to be particularly susceptible to the toxin. The midwives were erring on the side of caution.”

Actually, 1080 is not a known endocrine disruptor. Toxicologists such as Charlie Eason, professor of wildlife management at Lincoln University and research director at pest-control company Connovation, define such agents as “chemicals that act on hormones like oestrogen or androgen activity”, but neither 1080 nor its metabolite, fluoro-citrate, has been found to do so. Does it cross the placental barrier? It’s true that the fetuses of lab rats exposed to high doses of 1080 have suffered developmental defects, but the subjects were fed the toxin daily during the most active period of gestation before any observable effect occurred. However, it remains unclear how a pregnant woman (or anybody, for that matter) could end up ingesting such high doses of 1080 at all.

Bait stations are an effective method of possum control in accessible areas. Dave Fowler resets a trap that has reduced possum numbers by one.

But the bad press continues. Writing on the KAKA 1080 website in a piece entitled “The Truth and Nothing but The Truth”, hunter and outdoor lobbyist Hans Willems insists that 1080 “is so toxic that skin contact, inhalation, contact with the eyeball or ingesting as little as 0.06 of a metric gram, said to be the size of a full stop, means certain death”.Such claims might accurately refer to raw 1080, the form in which it leaves the lab (although even then, Willems’ figures are dubious). However, in New Zealand, only a few factory staff are exposed to the toxin in that concentration. It is then mixed into either carrot or cereal baits, of which actual 1080 makes up either 0.08 per cent of small baits or 0.15 per cent of large.

Also, aerial operations typically sow 5 kg of bait per hectare, which means that one hectare is left with between 4 and 7.5 grams of toxin spread over it—or, put another way, around 1000 baits, containing a teaspoonful of 1080 between them. Eason cites a highly conservative LD50 (a standard toxicology term referring to the lethal dose needed to kill half of a tested sample) of 1080, which is one milligram per kilogram of body weight. That is, a person who weighs 70 kg would need to ingest 70 mg (or seven bait pellets) for it to be fatal. “Who’s going to be doing that?” he asks. “It doesn’t actually happen.”

If Eason sounds frustrated, it’s unsurprising. There has never been a human death related to ingesting 1080, and he has been restating the facts for decades. Yet hyperbole like Willems’ has found currency as an urban—make that largely rural—myth.

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John Cumberpatch is the head of DOC’s 1080 operations. His job is to wrest threatened species from the jaws of stoats, rats and extinction. He has witnessed the tremendous benefits of 1080 on our maligned native species. “The science isn’t perfect—it never is—but we conduct a residual trap catch after every operation, and we know that the knockdown of pests is huge,” he says. “And it lasts longer than we once thought. We used to think that it was only two or three years; now it looks more like four or five years.”

There are several reasons 1080 remains the aerial bait of choice. A single aerial drop of 1080 can kill around 98 per cent of possums and will have a similar success rate on rats. Then it kills any other pests that feed on the carcasses (1080 can persist in dead tissue for months), after which it is metabolised by bacteria and disappears.

The fishing industry use the term by-catch, the military establishment call it collateral damage. In pest control they are non-target species. Images from the Graf brothers’ latest film showing weka investigating 1080 baits (top). A deer alleged to have died from 1080 poisoning (bottom), have sparked indignation among anti-1080 and animal welfare groups.

The respite it provides gives native birds a vital few seasons to procreate in peace. Experiments have shown what that means for the survival of species such as kaka, which have been monitored at three unprotected sites, and compared with three others under intensive pest control. At Lake Rotoroa, in Nelson Lakes National Park, unprotected kaka made 10 attempts to nest; only one succeeded. Over the next ridge, in the comparative sanctuary of the Lake Rotoiti “mainland island”, 12 out of 14 attempts produced fledged chicks.

It’s the same story on the Tonga-riro rivers, where stoats were sending whio—our blue duck—straight down the creek. In 2004, 10 pairs lost every last duckling. This season, 11 chicks survived to independence, aided by ongoing trapping.

Kiwi have also ridden the wave. Prior to the 1080 drop, just 12 per cent of kiwi chicks survived to independence. The next season, 56 per cent survived. And because 1080 also kills rats, the fantails got a break; chick survival leapt from 10 to 48 per cent.

But, for all the research, all the obvious benefits to biodiversity, and the role of 1080 in reducing bovine tuberculosis infections in farm animals to 0.34 per cent, there is more misinformation circulating about 1080 than ever.

You will still read bumper stickers insisting that “1080 kills everything”.

Psychologists call this “communal reinforcement”—the process by which a belief becomes fact in an ideologically aligned community. The phenomenon, as described by science writer and psychiatrist Ben Goldacre in Bad Science, “is independent of whether the claim has been properly researched, or is supported by empirical data…Communal reinforcement goes a long way to explaining how…testimonials can supplant and become more powerful than scientific evidence.”

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Eason says that while much of the fearmongering is “emotive and a little foolish”, he concedes that some concerns are “very understandable”.

That’s because for all the official assurances of strict controls, things have gone seriously wrong at times. A disastrous regional council 1080 operation in Upper Hutt in 2001 poisoned a number of family dogs which had scavenged dying possums that had crawled onto properties. Seven kea died after eating 1080 baits at Franz Josef only last year, and a West Coast farmer blamed the deaths of 10 farm deer on misplaced 1080 baits.

Wildlife protection programmes like DOC’s Operation Ark—here in the Hawdon Valley in Arthurs Pass—target stoats and rats that run riot when beech forest masts, causing a predator/prey pile-up that leaves native bird populations in tatters.

Wellington medical officer of health Stephen Palmer, whogives consents to regional 1080 drops, says he’s had to push pest-control authorities “very hard to improve the way they operated. Some of them were real cowboys.” Since then, he says, “there’s been a huge revolution in the way 1080 has been handled”.

He’s the first to concede that the 1080 debate has strayed from fact. “It’s about people’s perception of risk more than the actual risk. If you don’t address people’s perceived fears, then they remain.”

Phil Cowan, a science leader at Landcare Research, agrees: “We need to find better ways to try to talk about these issues. We’ve gone beyond the science debate, even though 1080 is probably the most researched vertebrate toxin anywhere in the world. Things are often so confrontational that there’s no real progressive discussion.”

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So are 1080’s days numbered in New Zealand? ERMA’s endorsement, stresses the authority’s general manager of hazardous substances, Andrea Eng, is provisional. “It’s not a green light; it’s an amber light—proceed with caution. It’s not an approval for all time.”

But, in the absence of a proven alternative, it’s unlikely 1080 will be banned. Fast-breeding pests would reclaim the forest in a few seasons. While anti-1080 groups insist that bait stations, bounties and trapping can achieve anything a helicopter drop can, hard experience and accounting prove otherwise.

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Bait stations work well, but they require regular tending and do nothing to stop dogs taking poisoned carcasses. In fact, possums can take in much bigger doses of poison from a bait station, making their remains even more lethal. It is true that in easy country, bait stations can be as economic as aerial 1080, but there are places in the hinterland so dauntingly steep, remote or downright ornery that they’re beyond even the hardiest trapper (the majority of whom prefer to work easier, more profitable countryside anyway). Says Cumberpatch: “It’s simply not possible to spread poison on foot in remote locations. It cannot be done.” Bounties have also been tried before, but ended up achieving little more than the illegal release of more possums.

In many ways, 1080 is the ideal weapon, taking out a host of pests in one hit—but this includes deer, a collateral casualty the hunting lobby will not brook. The Deerstalkers Association helped fund the Graf brothers’ anti-1080 DVD, although Clyde Graf unrepentantly bats away charges of self-interest. “I love seeing deer out in the wild. This country is better off for having them. Don’t give me evolution stories and all this nonsense… deer are here, and we’re not getting rid of them.”

Such comments convince Charlie Eason of the need for more pest-control options. “There’s a gap between conventional poisons and the demands and expectations of modern biocontrol that need to be filled,” he says.

“Even if you’re an advocate of 1080, you could see that having a range of tools at least takes the pressure off 1080 use.”

It might be the best we have, but public concern and hunting-lobby pressure are driving a quest for non-toxic controls, or at least more species-specific toxins. The development and adoption of such controls will, agencies hope, ease hostility towards their pest-control programmes, but they will bring problems of their own.

We already know that when stoat numbers are knocked down, rat numbers can soar in their absence, a catastrophe for native birds. That means any operation aimed at stoats will have to simultaneously tackle rats, to avoid a plague. Our grasp of pest dynamics will have to be meticulous, our timing impeccable.

Whatever innovations may come (see boxes in this feature), pest control is a job for life, or at least for the foreseeable future. “People think you can control pests and that’s the end of the problem,” says DOC scientist Elaine Murphy. “They don’t understand that you can hit them for one season, but you’re back to square one the next. That’s not a failure of pest control; it’s just something you have to keep doing, like track maintenance.

“I’d hate for us to walk away now. We can’t protect all the species we have, but I’d like for us to try and protect as many as we can, because I think in 20 or 30 years’ time, people will look back, and ask, ‘Why on Earth didn’t they do that little bit to keep that species?’”

Beyond 1080: Poisonous Prospects

P-aminopropiophenone. Little wonder those in the trade call it simply PAPP, an acronym for what could be the next big thing in pest-specific toxins. The poison kills quickly, taking 40 minutes on average, compared to the hours it takes for 1080 to work and the days involved with brodifacoum, a highly lethal anticoagulant poison. PAPP kills humanely and, unlike 1080, selectively, without secondary poisoning.

“PAPP represents the first new candidate vertebrate pesticide for more than 30 years,” says Charlie Eason, professor of wildlife management at Lincoln University and research director at pest-control company Connovation. He says it could be­come the platform for a new suite of tailor-made toxins, each specifically formu­lated to tackle a particular pest.

PAPP is what’s known as a red blood cell toxicant; it inhibits the transport of oxygen to the brain, killing in much the same way as cyanide. A collaboration between DOC and Connovation, PAPP has been tested on feral cats and dogs, but shows the most promise against stoats; field trials of the toxin at Waitutu in southern Fiordland last August killed 90 per cent of stoats in the area. “PAPP has a simple antidote and no residue, so it’s got all the…things that you would like to have in a toxin,” says Eason.

But good things take time. PAPP will need to be approved by the Food Safety Authority and the Environmental Risk Management Authority.

Eason says PAPP will initially come in two forms: as a meat bait for use in bait stations and as a paste for use in a dispenser attached to a tunnel or trap. The idea is that, as a stoat enters the tunnel or trap, the dispenser will dab the paste onto its fur as it passes. The stoat will lick the lethal paste off while grooming its coat.

Elaine Murphy, a DOC scientist who specialises in pest biology, says PAPP can also be used, at a higher dose, on feral cats and has been shown to work on dogs, which could help to protect kiwi from rogue pig dogs lost in the bush. Unfortunately, she says, it doesn’t work well on rats. “None of these things are perfect.”

Brodifacoum has for years been the rat toxin of choice, but since it was shown to persist in the food chain (it was detected in the livers of feral pigs and deer), DOC has sharply curbed its use on the mainland. A replacement, says Murphy, could be diphacinone, another anti-coagulant already used in the United States for aerial rodent-control operations. “Diphacinone is good, because if something gets a sub­lethal dose, it gets cleared from the body really quickly.”

But diphacinone is non-selective; non-target species can still die, as did 70 short-tailed bats at Pureora early this year. “All these options have pluses and minuses,” Murphy says.

Rats are a soft target compared to one of our most voracious—and canny­ pests, the wild pig. A favourite of hunters (some of whom routinely liberate them into bush around the country), pigs root up vast areas of regenerating forest, leaving neatly ploughed ground for invasive weeds such as wilding pines. They also wreak havoc in seabird colonies, digging out chicks and eggs, and hoover up native snails.

But so far, they’ve proven too smart to poison; a well-developed vomit reflex means they reject a poisoned bait the moment they feel sick, and they learn well—a poisoned pig won’t make the same mistake twice.

To date, the only toxins that have worked on pigs, like phosphorus, have caused too much suffering to be acceptable, but the solution may rest with a simple food preservative. It turns out that pigs are susceptible to sodium nitrate, a chemical added to processed meats to retain their colour. It works much like PAPP, inhibiting oxygen supply to the brain, explains Murphy. “We’ve done trials here and in Australia and it seems to work really well. We’re just at the beginning, but it’s quite exciting. The idea would be to find something like that for possums and rats as well.”

Beyond 1080: Scrambling the egg

Before we can kill a possum, we have to know how it lives—or, better still, how it loves. Possums can be promiscuous; males will mate with several females over the breeding season, which is triggered by shortening days. By mid-March, a possum’s thoughts are all about sex.

Females give birth in the autumn to a single baby after a fleeting gestation of 17 days. So incomplete are the young when they crawl to the pouch (roughly equivalent to a four-and-a-half-month-old human fetus) that even biolo­gists are unable to determine their sex for another few days. They have few digits, no reproductive tract and—to the intense curiosity of Landcare Research scientist Janine Duckworth—almost no immune response.

Duckworth is looking for a way to stop possums breed­ing, part of an eight-year, $21 million multi-agency pro­gramme funded by the Foundation for Research, Science and Technology.

She and her colleagues have tried a suite of foils, but the greatest hope for our forests may rest in a transparent membrane, the zona pellucida (ZP), which surrounds every possum egg as it develops in the ovaries. It contains special receptors that receive the male’s sperm and help it to pen­etrate and fertilise the egg. Interrupting this process could be the vital stop-gate to stem the possum tide. It may even be possible to induce the possum’s own immune system to mount an attack upon the eggs in its ovary.

In trials, three ZP proteins were injected into captive possums, producing 80 per cent infertility. But it would be impossible to inject every possum in the country; Duck­worth must find a way to get those proteins into the wild animals. The solution could be very small—just the “ghost” of a bacterium.

Think of Duckworth’s biocontrol as a missile; the bacterium is the rocket that carries the ZP protein—the warhead—to its target. Her team injects two proteins into a bacterium, such as E. coli. One is the ZP protein. The other protein punches holes through the bacterium’s outer coat, draining the cell’s contents. All that remains is a husk—called a bacterial ghost—with the ZP protein safely tucked within. “The possum’s body recognises the bacterial ghost as foreign,” says Duckworth, “and will try to remove it. In doing so, it recognises the zona pellucida as foreign as well.”

Bacterial ghosts are a mixed blessing; being “dead”, they can’t be transmitted from one animal to another, which allays concerns that a biocontrol agent could somehow jump the Tasman and infect possums in their homeland. However, using them also means we can’t get possums to spread the ZP protein for us; populations would have to be periodically re-treated.

Then there’s the question of how to deliver the protein across tens of thousands of hectares. The most promising method for now is to feed it to possums in an edible bait.

Trials have shown the protein can cut possum fertility by 40 per cent, but only for one breeding season. To be truly ef­fective in the wild, it must last at least two seasons. Funding permitting, the team will try to build a better bacterial ghost, capable of delivering more of the protein.

Landcare Research science leader Phil Cowan says that if they can do that—and get infertility up to 70 per cent—the ZP protein could make for a potent weapon in the armoury. It won’t eradicate possums altogether, but it will back up existing controls by “slowing down the rate at which pos­sum numbers recover. This potentially reduces the amount of toxins we would have to use.”

The savings could be massive; models show a 70 per cent reduction in fertility could make poisoning operations neces­sary only every 10 or 12 years. Above 80 per cent, says Cowan, could mean that local or even regional eradication is possible.

Beyond 1080: A trap for young players

In tongariroforest along the rowdy, roiling reaches of the Whakapapa River, Dean Flavell and Bubs Smith maintain lines of DOC 200 traps, set for the stoats and rats that plague nesting whio, or blue duck.

While the ducks are breeding, Flavell and Smith will visit all 650 traps once a fortnight, emptying, baiting and resetting lines here and along the Mangatepopo and Upper Whanganui headwaters. It’s a fulltime job.

Across Aotearoa, thousands of DOC 200s lie in wait for hungry, inquisitive predators. Inside a wooden box, their doom is decided by a hair trigger—a lethal steel bar under hundreds of kilograms of latent pressure from a muscular spring. The moment a stoat sets foot on a pressure plate, the energy is released, bringing down the bar with crushing force.

It’s ruthlessly effective and very humane, but it has one critical flaw. The DOC 200 that Flavell has just re-set might kill a stoat this very night but, once sprung, it won’t kill again until he returns in two weeks.

And stoats—voracious and rapacious—can do a lot of harm in a fortnight. Right now, many of those DOC 200s in the backcountry, having been triggered, are off-duty, an unten­able inefficiency in what is a hard-fought numbers game with high stakes. A DOC 200 costs around $55, yet this is small change against the enormous investment of labour required to service one.

Darren Peters, a DOC pest-control expert, knows there’s no extra money coming in, yet somehow “we need to be able to do larger areas with the same money”.

For years, conservation managers have dreamed of a trap that could go on killing untended and unbaited, one that could empty and re-set itself. Enter Goodnature, a trio of young Wellington industrial designers who have realised the dream.

Stu Barr shows me a tough plastic housing with stainless-steel fittings, built to last 20 years. Normally, it would be mounted to a tree trunk, 30 cm off the ground. The downwards-facing funnel is an irresistible invitation to stoats, pathologically curious, investigative hunters. To peer into a Goodnature trap, it would have to stand on its hind legs, sup­porting itself with its front feet. When 80g of downward force is applied to a pressure-sensitive treadle, it fires a CO2 canister which propels a piston at lightning speed into the body of the trap, crushing the stoat’s head in a heartbeat.

Gravity then resolves the biggest problem in contemporary trapping; the stoat falls out of the trap, leaving it clear for the next. The CO2 canister has spent just a fraction of its am­munition; it’s good for another 11 kills. The trap hisses as it resets—the sound of a portent, of the turning of a tide.

Goodnature’s trap costs $160, three times more than a DOC 200, but it could save conservation a fortune. “In five years, you basically halve your labour costs, from $4 million to $2 mil­lion,” says Barr.

Currently Flavell can fit only four DOC 200s in his pack at a time, which will collectively kill four stoats each time they’re set. But if he filled his pack with 20 Goodnature traps instead, he could despatch 440 stoats a month. “Buy a single-action DOC 200,” says Peters, “put it in a box, carry it into the bush, check it 12 times a year—that’s $1800 per trap over 20 years. Buy one of these,” he says, pointing to the Goodnature trap, “put it on site, check it for 20 years; $450.”

Barr says the trap has killed rats in field trials too, despite the fact that it doesn’t need baiting. Already, DOC has funded research and development for a self-resetting possum trap. A tiny CO2 cartridge may be the saviour our wildlife has been waiting for.